<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Document</title>
</head>

<body>

</body>

</html>
<script>
  // 求 1~10之间的所有偶数和
  var sum = 0;
  for (var i = 1; i <= 10; i++) {
    if (i % 2 === 0) {
      sum += i;
    }
  }
</script>